// Created by Armin on 2/10/2025.

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pp = pair<int, int>;
using vi = vector<int>;
using v = vector<int>;
using vvi = vector<vector<int>>;
using vpi = vector<pair<int, int>>;
using vl = vector<ll>;
constexpr ll MOD = 1e9 + 7;

void solve() {
  int n; cin >> n;
  vector<int> mi(n);
  for (int i = 0; i < n; i++) {
    cin >> mi[i];
  }
  vector<vector<int>> neighbors(n);
  for (int i = 0; i < n - 1; i++) {
    int a, b; cin >> a >> b;
    a--; b--;
    neighbors[a].push_back(b);
    neighbors[b].push_back(a);
  }

  for (int i = 0; i < n; i++) {
    int minus = 0;
    vector<int> mn;
    for (int& j : neighbors[i]) {
      if (mi[j] == -1) {
        minus++;
        mn.push_back(j);
      }
      if (mi[i] == -1 && mi[j] == -1) {
        cout << "NEM\n2\n" << i + 1 << " " << j + 1 << "\n"; return;
      }
      if (minus >= 2) {
        cout << "NEM\n3\n";
        cout << mn[0] << " " << i + 1 << " " << mn[1] << "\n"; return;
      }
    }
  }
  cout << "IGEN\n";
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);
    
    int t; cin >> t;
    while (t--) {
      solve();
    }
    
    return 0;
}